Arca contributed to Bjork's Cornucopia project, which Bjork performed at The Shed in NYC earlier this year, and during Arca's own run at The Shed this past weekend, Bjork came out during the Friday (9/27) show to perform an unreleased song from act 3 of Arca's new piece Mutant;Faith. Arca introduced her by saying "It is my pleasure to introduce you a friend of mine to sing with me, she is Björk," and part of her performance was sung in Spanish. Watch video below.